The invention relates to an injection anchoring sleeve of plastic.
Injection anchors are used for anchoring components or articles to wails of hollow blocks or concrete or other masonry walls, wherein it is important to obtain a good connection which is not only based on friction, but which provides for locking or self-substance retention.
To this end, injection anchors comprise an injection anchoring sleeve, which is known in various forms, injection mortar which, after insertion of the injection sleeve, is introduced into the sleeve opening and an anchoring bolt which is then inserted into the anchoring sleeve and which has a profiled, that is generally threaded, outer surface by way of which it is engaged with the mortar and/or the sleeve.
In order to facilitate a positive locking in hollow blocks, or respectively, a substance retention of the injection mortar in the bore hole wall, various kinds of injection anchoring sleeves have been proposed and are in use. A common embodiment of such injection anchoring sleeve is the so-called sieve sleeve wherein the sleeve wall consists of a sieve-like lattice structure.
Such sieve sleeves of metal or a metal wire lattice structure or, respectively, plastic sleeves reinforced with a metal wire lattice structure however are expensive and complicated to manufacture. Sieve sleeves which consist only of plastic can be manufactured by injection molding techniques and are therefore substantially less expensive to manufacture. They permit furthermore design variations, for example, outwardly projecting elastic flaps may be provided, but they have the disadvantage that they are not permitted for many applications by construction regulations because such sieve sleeves may not provide for the required pull-out resistance values and such sieve sleeves of plastic will not comply with the friction locking requirements.
With regard to form-locking anchoring of the sleeves in hollow block walls, conventional sieve sleeves of plastic and also of metal or of plastic-metal compound structures have the disadvantage that the flow of the injection mortar through the sieve openings of the sleeve into the openings of the wall blocks is not reliably controllable so that it is not known whether the mortar passing outwardly through the sieve comes into firm contact with drilled-through wall material or whether it is discharged somewhere else into a chamber of a hollow block.
Another known injection anchoring sleeve includes an elastic stocking disposed on a plastic support structure. In this arrangement, the injection mortar does not flow through the stocking but expands it radially in the area of the block chambers and provides therefore for a quite reliable form-fitting locking of the anchoring sleeve. However, because the injection mortar will not adhere to the bore walls, this type of anchors are not suitable for anchoring injection anchoring sleeves in concrete walls. It also does not provide for a safe friction locking in the bore drilled into the concrete wall.
It is the object of the present invention to provide an injection anchoring sleeve of plastic, which cannot only be manufactured in a simple and inexpensive manner by injection molding but which also has excellent anchoring properties for locking the anchoring sleeve in concrete, in hollow block walls and other masonry walls, for locking in a form-fitting manner and also by substance retention and frictional engagement of the anchoring sleeve.
In a plastic injection anchoring sleeve having an essentially cylindrical sleeve body with a closed front end and an open opposite end for the insertion of an anchoring bolt, the sleeve wall has a plurality of openings closed by flaps which are formed integrally with the sleeve and pivotally supported thereby at their front ends, the flaps being provided with axially extending ribs projecting radially inwardly and having inclined front and rear end portions forming ramps for lifting the flaps outwardly out of the openings when the sleeve body is removed axially from a molding core after injection molding or when an anchor bolt is inserted into the sleeve body.
The arrangement according to the invention provides for the following advantageous results:
The injection anchoring sleeve according to the invention can be manufactured by injection molding in a single piece wherein the radially inwardly projecting ribs of the flaps are formed by corresponding radial recesses in the essentially cylindrical mold core forming the hollow interior of the anchoring sleeve. When the injection molding step is completed the finished anchoring sleeve is pushed axially from the cylindrical mold core wherein, because of the slopes of the ribs, the flaps are pivoted about their front joints with the sleeve radially outwardly. As a result, the ribs are lifted out of the radial recesses of the cylindrical mold core and the anchoring sleeve can be pushed off the mold core without any problems. At the same time, it is ensured in this way that the flaps will not remain firmly attached to the sleeve walls, but can be pivoted outwardly into their operational positions where they act as barbs when the anchoring sleeve is later inserted into an anchoring bore.
Upon installation of the anchoring sleeve into an anchoring bore, the flaps are again pivoted inwardly. Where there are openings in the masonry that is in areas of open chambers in a hollow block, the flaps will again pivot outwardly somewhat. They are pressed outwardly when the injection mortar is introduced under pressure into the auxiliary sleeves. Since the flaps are attached at their front ends to the anchoring sleeve body whereby they are pivotally supported (the thin wall connection acts as an elastic joint) the radially outwardly pivoted flaps extend backwardly at an angled orientation (with regard to the insertion direction) and, in this way form a rearwardly directed discharge opening for the injection mortar. In this way, the injection mortar flows backwardly from the anchoring sleeve in form-locking abutment with the hollow chamber walls of the hollow blocks.
Flaps, which are not, or not fully, opened are opened at the latest when the anchor bolts are inserted into the anchoring sleeves. The front ends of the anchor bolts cooperates with the inclined rear rib portions so that the flaps are forced outwardly by the anchor bolts during insertion of the anchor bolts into the anchoring sleeves. Where the flaps cannot yield outwardly because they are disposed in solid wall areas of the masonry wall, that is, where they are engaged by the walls of the bores in the hollow blocks, the respective ribs are compressed by the anchoring bolt, which is pressed hammered or screwed into the anchoring sleeve. The compression of the ribs provides for radial clamping between the anchor bolt and the bore wall so that, in these areas, a firm friction fit is provided. In this way, the additional advantage is achieved that the anchor bolt is centered in the anchoring sleeve according to the invention by the ribs extending inwardly from the flaps essentially over the full length of the anchoring sleeve, which is generally not the case with conventional injection anchors. With injection anchors, a certain clearance has to remain between the inner anchoring sleeve surface and the anchor bolt for receiving the injection mortar since otherwise an engagement between the injection mortar and the anchoring bolt is not possible. The injection anchoring sleeve according to the invention fulfills all the criteria of the object of the invention.